Arris/Motorola SB6121 DOCSIS 3.0 Cable Modem in Non-Retail Packaging (Brown Box) DOCSIS 3.0 certified, capable of up to 172 Mbps and upload speeds up to 131 Mbps based on Cable Internet Service Provider Supports IPv4 and IPv6 networking, as well as Windows, Mac, and Linux computers 10/100/1000Mbps Ethernet port to connect with router or computer Requires Cable Internet Service. Compatible with major U.S. Cable Providers. Contact your ISP to confirm compatibility. Front-panel LEDs indicate status and simplify troubleshooting Tips* Reorient or relocate the receiving antenna. Increase the separation between the device and receiver. Connect the equipment into an outlet on a circuit different from that to which the receiver is connected. . Consult the dealer or an experienced radio/TV technician for help.